It is known to form an image of a cross section of a flowing fluid by means of a camera, the image being captured by an optical element serving spectral dispersion, and to process the radiation so spectrally dispersed by means of a sensor array read out serially. That is, the image of the fluid cross section is "one-dimensional" or line-shaped, the inlet aperture of the camera having a slot-like shape.
It is an object of the present invention to provide an apparatus for optically monitoring a space and which is of simple design.
It is a further object of the invention to provide such an apparatus that is also adapted to determine the distribution of radiation emanating from or absorbed by a flowing fluid in a flue of a steam generator, the resolution requirements being moderate.